That said, since these are BMW OEM options, im comparing the products "as-is".
For those 2 products specifically, their EU tire label also shows similar discrepancy in noise on a like-size basis.

Which is exactly the sizes I swapped around with on my M235i. I remember the day I put the MPSS back on as I'd sold the car and the 19's and remember thinking. How noisy they were. But there you go. It's all about perception.

If it helps I ran my car with some RFT (Bridgestone 18") for a short period recently as I am selling the wheels they are on and liked the look so thought I'd put them on the car, have to say I was massively surprised as they have come on in leaps and bounds from when I used to have them on a 335d in 2008. I do have adaptive so this may help but I had no issue with them apart from the usual thump over cats eyes when over taking. I certainly wouldn't rush to change them until worn, yes I'd prefer MPSS but the RFT are by no means a bad choice so enjoy the new car when it arrives
In terms of grip at this time of the year I never noticed any issues at all, no increased wheel spin etc when pulling out of junctions, I'd say just give them a good try .

I picked it up today, pretty damn chuffed. It seems more refined and quieter inside than my '14 M135i - the fake noise is barely detectable really. Anyway, it did come on Bridgestone Potenza S001 runflats. I'll see how I get on with them, but really I would prefer the proper tyres.

The car looks great, good work! When it comes time to change I would highly recommend changing to normal tyres. I run Michelin PS4's on my M140 now and have genuinely found it night and day to the run flats in terms of ride comfort and handling. Get the pressures right and you're away.
Alex

Went out this morning now it's sat overnight and cooled to find the dealer had let it go with 41 in the back and 37 in the front - should be 35 all round. Why do dealers always get this simple thing worng?!